1. Field of the Invention
The present invention relates to a wireless transmitting device and a wireless transmitting method.
2. Description of the Related Art
A short-break-free wireless communication technology applicable to voice speeches, radios, low-pixel television broadcasting, etc has been examined over the recent years. The technology under the examination is the wireless communication technology with no time delay larger than a predetermined limit value. Obstacles against realizing the short-break-free wireless communications are interference between radio signals received via different propagation routes and screening on the propagation path. These phenomena are called fading and shadowing. A wireless communication method and a wireless communication device, which are effective in reducing these phenomena, are required for actualizing the short-break-free wireless communications.
What is focused as a technology having a possibility thereof is a communication technology based on space time block coding (STBC) for obtaining diversity by transmitting encoded data from a plurality of antennas on a transmitting side and a communication technology to which time diversity is applied.
The STBC is a technology for obtaining spatial diversity by transmitting signals from transmitting antennas spatially away from each other on the occasion of sending the same data by use of a plurality of transmitting antennas.
By contrast with the STBC, a time diversity method is a technology for obtaining time diversity and enhancing a quality of the wireless communications by transmitting signals distanced in time a plural number of times.
On the other hand, in recent years, a technology enabling large-capacity data communications as of images etc has been examined. The prior art is a communication technology based on a MISO (Multiple-Input Single-Output) architecture defined as a technology of receiving communication signals transmitted from the plurality of transmitting antennas by a single receiving antenna. However, a communication technology based a MIMO (Multiple-Input Multiple-Output) architecture defined as a technology of receiving the communication signals transmitted from the plurality of transmitting antennas by a plurality of receiving antennas, is examined for enabling the larger-capacity data communications.
FIG. 1 shows an example of a wireless terminal device based on the MISO architecture. A transmitting station has a plurality of transmitting antennas, while a receiving station has a single receiving antenna. In FIG. 1, the MISO architecture is exemplified by assuming Wideband Code Division Multiple Access (W-CDMA).
FIG. 2 shows an example of a wireless terminal device based on the MIMO architecture. The transmitting station has the plurality of transmitting antennas, and the receiving station also has the plurality of receiving antennas. In FIG. 2, the MIMO architecture is exemplified by assuming Beyond 3G (Beyond Third Generation (3G) Mobile Communication System).
FIG. 3 illustrates examples of communication procedures applicable to the MIMO architecture communication system, wherein the communication procedures are categorized into data transmission conducted a plural number of times and diversity transmission. In the case of the communications based on the MIMO architecture, the multi-transmission technology is exemplified by BLAST (Bell Labs Layered Space-Time), E-SDM (Eigen-Space division Multiplexing), etc. On the other hand, in the communications base on the MIMO architecture, the diversity transmission technology is exemplified by the STBC and the time diversity method.
In these technologies, the diversity transmission is a communication procedure suited to the short-break-free wireless communications.                [Patent document 1] Japanese Patent Application Laid-Open Publication No. 2000-269929        [Non-Patent document 1] “A Simple transmit diversity technique for wireless communications” authored by Siavash M. Alamouti, IEEE Jour Sel. Areas in Com, U.S.A., IEEE, October in 1998, vol. 16, no. 8, pp. 1451-1458.        [Non-Patent document 2] “Space-Time Block Codes from Orthogonal Designs”, authored by V. Tarokh et al., IEEE Trans on Info Theory, U.S.A., IEEE, June in 1999, Vol. 45, no. 5.        [Non-Patent document 3] “A quasi orthogonal space-time block code”, authored by H. Jafarkhani, IEEE Trans. Comm., U.S.A., IEEE, April in 2003, vol. 49, pp. 287-291.        [Non-Patent document 4] “Results of Outdoor Experiments for Auto-Correlativity of Shadowing Using Downlink OFDM Broadband Wireless Access”, authored by Morimoto, et al., Proceedings at the 2004 General Meeting of the Institute of Electronics, Information and Communication Engineers, in the year of 2004, B-5-90.        [Non-Patent document 5] “Correlation Model for Shadow Fading in Mobile Radio Systems”, authored by M. Gudmundson, Electronics Letters, U.K., IEEE, 1991, Vol. 27, no. 23, pp. 2145-2146.        